N Korea nuclear test 'grave threat to peace and security': Monitor

Seoul: The head of an international body set up to monitor a ban on nuclear testing condemned North Korea`s fourth nuclear test on Wednesday.

"This act constitutes a breach of the universally accepted norm against nuclear testing," Lassina Zerbo, head of the Comprehensive Nuclear-Test-Ban Treaty Organisation which monitors a ban on nuclear tests told Reuters.

"It is also a grave threat to international peace and security," he said.